1. Field of the Invention
This invention relates to a method of making a semiconductor device, more particularly to a fine process necessary for the production of a semiconductor LSI (large scale integrated) circuit.
2. Prior Art
In the conventional method of making a semiconductor device, a photo-sensitive resin film (photoresist film) is employed for a production of an IC (integrated circuit). However, the photoresist film is inherently not heat resistive, and therefore its use is limited to processes, during which it is not heated above 200.degree. C. When the photoresist film is used to obtain a fine photoresist film pattern and if it is heated above 200.degree. C. in a subsequent production process, then the photoresist film per se is softened and the fine photoresist film pattern changes the original shape thereof. This leads to undesirable outcomings in that the width of the fine photoresist film pattern spreads and top edges of the fine photoresist film pattern shape round. Moreover, the thickness of the film pattern decreases after it is heated at a high temperature.
It is substantially necessary in the conventional IC production process that the photoresist film is removed before it is subjected to a heating process.